This invention relates generally to gas turbine engines and more particularly to shroud assemblies utilized in the high pressure turbine section of such engines.
A gas turbine engine includes a compressor that provides pressurized air to a combustor wherein the air is mixed with fuel and ignited for generating hot combustion gases. These gases flow downstream to one or more turbines that extract energy therefrom to power the compressor and provide useful work such as powering an aircraft in flight. A turbine section commonly includes a stationary turbine nozzle disposed at the outlet of the combustor for channeling combustion gases into a turbine rotor disposed downstream thereof. The turbine rotor includes a plurality of circumferentially spaced apart fan blades extending radially outwardly from a rotor disk that rotates about the centerline axis of the engine.
The turbine section further includes a shroud assembly located immediately downstream of the turbine nozzle. The shroud assembly closely surrounds the turbine rotor and thus defines the outer boundary for the hot combustion gases flowing through the turbine. A typical shroud assembly comprises a shroud support which is fastened to the engine outer case and which in turn supports a plurality of shrouds. The shrouds are held in place, in part, by arcuate retaining members commonly referred to as C-clips. Specifically, the C-lips hold the aft end of the shrouds in place against the shroud hangers via an interference fit.
The interference fit normally provides excellent retention of the shrouds. However, there can be a tendency for the C-clips to back off in some instances because of a thermal ratcheting phenomenon. That is, although the shrouds and C-clips are segmented to accommodate for thermal expansion, there is a possibility that the thermal loads within the shroud assembly can overcome the interference fit clamp loads. In some cases, there may be enough of a gap between the C-clip aft face and the adjacent nozzle outer band to allow for C-clip disengagement. Such disengagement could result in severe hardware damage.
Accordingly, there is a need for a shroud assembly design that eliminates C-clip back-off.
The above-mentioned needs are met by the present invention which provides a shroud assembly including a shroud support having a hook and at least one shroud having a mounting flange. A C-clip overlaps the hook and the mounting flange to clamp the shroud to the shroud support, and a retainer is secured to the shroud support and located so as to engage the Clip. The retainer engages the C-clip in such a manner so as to limit aft axial movement of the C-clip, thereby eliminating C-clip back-off.
Other objects and advantages of the present invention will become apparent upon reading the following detailed description and the appended claims with reference to the accompanying drawings.